This woman called Koharu kept calling me during the game, and I had no idea who she was so I figured it would be revealed later in some weird plot twist. But nothing ever happened. Turned out she's a girl from one of the Gigolo missions, and if you don't do those missions the girls get annoyed and call you up to bug you while you're doing the proper missions.

So getting AAA rankings on the missions is how you unlock stuff. Although it only adds it to the shop, and then you have to buy it. A bunch of costumes for Mondo are added to the shop after beating the game, but they cost a lot.

I haven't played the side missions at all yet, which I gather is how a lot of the costumes are unlocked, but getting AAA on the story missions has so far just unlocked lingerie which you can give to the women as presents during Gigolo missions.

Wow, upgrading the robot arm makes a big difference. I'd forgotten all about it until I realised I had 1600 upgrade points lying around. At level 3 the gun arm slows down targets just by aiming at them. It's really weird actually, it only slows down the specific enemy your aiming at, and only when the reticule is actually on them. Mondo and all the other enemies still move at normal speed.

I should really do the other Gigolo missions to get the other two arms.